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Authors Das, S. K. ; Egorov, S. A. ; Virnau, P. ; Winter, D. ; Binder, K.
Title Do the contact angle and line tension of surface-attached droplets depend on the radius of curvature?
Date 01.06.2018
Number 55461
Abstract Results from Monte Carlo simulations of wall-attached droplets in the three-dimensional Ising lattice gas model and in a symmetric binary Lennard-Jones fluid, confined by antisymmetric walls, are analyzed, with the aim to estimate the dependence of the contact angle on the droplet radius of curvature. Sphere-cap shape of the wall-attached droplets is assumed throughout. An approach, based purely on thermodynamic observables, e.g. chemical potential, excess density due to the droplet, etc, is used, to avoid ambiguities in the decision which particles belong (or do not belong, respectively) to the droplet. It is found that the results are compatible with a variation , being the contact angle in the thermodynamic limit. The possibility to use such results to estimate the excess free energy related to the contact line of the droplet, namely the line tension, at the wall, is discussed. Various problems that hamper this approach and were not fully recognized in previous attempts to extract the line tension are identified. It is also found that the dependence of wall tensions on the difference of chemical potential of the droplet from that at the bulk coexistence provides effectively a change of the contact angle of similar magnitude. The simulation approach yields precise estimates for the excess density due to wall-attached droplets and the corresponding free energy excess, relative to a system without a droplet at the same chemical potential. It is shown that this information suffices to estimate nucleation barriers, not affected by ambiguities on droplet shape, contact angle and line tension.
Publisher Journal of Physics : Condensed Matter
Wikidata
Citation Journal of Physics : Condensed Matter 30 (2018) ID255001
DOI https://doi.org/10.1088/1361-648X/aac363
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